1. Field of the Invention
The present invention relates to an electric feeding method and apparatus for a continuous plating apparatus for continuously feeding electric power to articles to be plated.
2. Description of the Related Art
Conventionally, in order to plate planar articles, a plurality of articles to be plated are individually mounted by fasteners on a frame member connected to cathodes, and the articles are removed individually after the completion of plating. However, this method is time-consuming, and causes a hindrance against plating work.
Therefore, recently, an approach has been proposed in which, without fixing the articles to the frame member, the articles to be plated are continuously fed into a plating bath one by one, and the articles to be plated are moved in a vertical direction within the plating bath to thereby continuously effectively plate the articles.
FIG. 7 is a cross-sectional view showing an example of a continuous plating apparatus that may perform continuous plating. A V-shaped rail 2 in cross section extending in a vertical direction to the paper surface is provided in the vicinity of a central bottom of a plating bath 1. An article 3 to be plated such as a printed circuit board is held in the vertical direction with its lower edge being laid on the rail 2. Both surfaces of the article 3 are clamped by electric supply rollers 5 fixed to vertical rotary electrode shafts 4. The electric supply rollers 5 are rotated together with the rotary shafts 4 so that the article 3 to be plated is moved horizontally on and along the rail 2 under the condition that the article 3 is dipped in plating liquid 6. Then, anodes 8 which may move vertically by cylinders 7 and shielding plates 9 for preventing turbulence are provided in the plating liquid 6.
Wheels 10 are mounted at suitable positions of the rotary shafts 4 and pressing members 12 pressed by springs 11 are brought into contact with the wheels 10. The pressure force of the springs 11 is transmitted from the wheels 10 through the rotary electrode shafts 4 to the electric supply rollers 5 so that the contact between the electric supply rollers 5 and the article 3 to be plated is ensured and the flow of the electricity to the surfaces of the article 3 is made uniform.
Thus, the surfaces of the article 3 to be plated are charged with a negative potential from the rotary electrode shafts 4 through the electric supply rollers 5 so that the current flows from the anodes 8 to perform the continuous plating.
The circumferential surfaces of the electric supply rollers 5 which are brought into contact with the articles 3 to be plated are coated with a protection film which is made of titanium nitride on, for example, a nickel plated film that is harder than the plating coating to be applied, such as a copper film. Brushes 14 are pressed against the circumferential surfaces of the electric supply rollers 5 by springs 13 so that the plating formed on the circumferential surfaces of the electric supply rollers 5 may be removed.
Since each of the conventional electric supply rollers 5 as a whole is formed into a single conductive member, the current always flows also through a portion which is out of contact with the article 3 to be plated and a plating is formed on the electric supply rollers 5 as a whole.
Even if the brushes 14 are depressed against the circumferential surfaces of the electric supply rollers 5 by the springs 13 as mentioned above, it is difficult to remove the plating adhered over the entire electric supply rollers 5. Due to the accumulated plating, the electric supply rollers 5 are damaged so that the serve life thereof is shortened. A current will not uniformly flow through the articles to be plated. As a result, it is impossible to perform the plating work.